Field
The disclosed concept pertains generally to electromechanical apparatus and, more particularly, to electromechanical apparatus including a motor. The disclosed concept further pertains to electrical switching apparatus including a motor.
Background Information
An electrical switching apparatus typically includes at least one bus assembly having separable contacts, and an operating mechanism. The separable contacts include a fixed contact and a movable contact. Each contact is coupled to, and in electrical communication with, a conductive bus that is further coupled to, and in electrical communication with, a line or a load.
If the electrical switching apparatus is a circuit interrupter, then it typically includes a trip device structured to detect an overcurrent condition and to actuate the operating mechanism. The operating mechanism is structured to both open the contacts, either manually or following actuation by the trip device, and close the contacts.
In some circuit interrupters, the operating mechanism includes both a closing assembly having a number of closing springs and an opening assembly having a number of opening springs. These assemblies may have common elements that are structured to move the movable contact between a first, open position, wherein the separable contacts are separated, and a second, closed position, wherein the separable contacts are coupled and in electrical communication. The operating mechanism may also include a rotatable pole shaft that is coupled to the movable contact and structured to move each movable contact between the closed position and the open position. Elements of both the closing assembly and the opening assembly are coupled to the pole shaft so as to effect the closing and opening of the contacts.
In certain circuit interrupters, typically, the force required to close the separable contacts is greater than what a human may apply. As such, the operating mechanism typically includes a mechanical closing assembly to close the separable contacts. The closing assembly, typically, includes at least one stored energy device, such as a spring, and/or a motor. A common configuration includes a motor that compresses one or more springs in the closing assembly. The closing springs are coupled to a cam roller that engages a cam coupled to the motor. As the motor rotates the cam, the closing springs are compressed or charged. The closing springs are maintained in a compressed configuration by a latch assembly. The latch assembly is actuated by a user to initiate a closing procedure. The closing assembly is structured to apply the energy stored in the springs to a toggle assembly so as to cause the pole shaft to rotate and close the separable contacts.
The charging of the closing springs is typically accomplished via the motor. The motor has an output shaft that is coupled, directly or indirectly, to the shaft of the charging cam. In addition to the charging motor, most electrical switching apparatus include an elongated manual charging handle. The charging handle also acts upon the shaft of the charging cam either directly or indirectly.
Motors are frequently damaged in the field. Several potential causes include assembly error (e.g., without limitation, operator error in assembling a motor or its components in its intended application) and manufacturing error (e.g., without limitation, manufacturing or other defects in motor components).
There is room for improvement in electrical switching apparatus including a motor.
There is further room for improvement in electromechanical apparatus including a motor.